Experimental Evaluation of the Influences of Water on the Fracture Toughness of Mudstones with Bedding

Table 3

Mode I fracture toughness of Type B mudstone specimens for different soaking times.

Specimen number	Soaking time t (minutes)	Peak load Pcr (N)	Mode I fracture toughness KIc (MPa m^0.5)		Degradation degree (%)
			Test value	Average value
BI0-1	0	1768.1 ± 0.01	0.817
BI0-2	0	1839.5 ± 0.01	0.850	0.820	0
BI0-3	0	1716.2 ± 0.01	0.793
BI50-1	50	1603.6 ± 0.01	0.741
BI50-2	50	1508.4 ± 0.01	0.697	0.745	−9.15
BI50-3	50	1724.8 ± 0.01	0.797
BI100-1	100	1325.9 ± 0.01	0.615
BI100-2	100	1373.4 ± 0.01	0.640	0.623	−24.02
BI100-3	100	1318.4 ± 0.01	0.614
BI200-1	200	1157.8 ± 0.01	0.539
BI200-2	200	1218.4 ± 0.01	0.564	0.548	−33.17
BI200-3	200	1152.1 ± 0.01	0.541
BI300-1	300	1046.5 ± 0.01	0.443
BI300-2	300	1141.2 ± 0.01	0.480	0.452	−44.88
BI300-3	300	1026.3 ± 0.01	0.433